This invention relates to motors the motor effect of which can be employed in two different ways giving it an important but by no means exclusive application in apparatus for manufacturing metal matrix composite materials, i.e. metals incorporating particulate substances. The term "particulate substances" is used herein to include substances in chopped or short fibre form in addition to powdered and granular substances.
Very fine powders are difficult to make flow in a controlled manner and one means of producing a flow is to cause the material to vibrate. The present invention is based on the discovery that if a ring disposed substantially horizontally is caused to vibrate radially, preferably at its natural frequency, a flowable substance deposited on the upper surface of the ring moves to the central aperture of the ring and further, that material tends during its fall through the ring to move then towards the axis of the ring under the radial compressing force of gas present in the hole and vibrating at the same frequency as the ring.